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Test Code Porph Qnt Porphyrins Evaluation, Whole Blood

Reporting Name

Porphyrins Evaluation, WB

Useful For

Establishing a biochemical diagnosis of erythropoietic protoporphyria and X-linked dominant protoporphyria


Necessary Information


Include a list of medications the patient is currently taking.



Specimen Required


All porphyrin tests on whole blood can be performed on 1 draw tube.

 

Patient Preparation: Patient should abstain from alcohol for 24 hours.

Container/Tube:

Preferred: Green top (sodium heparin)

Acceptable: Dark blue top (metal free heparin) or green top (lithium heparin)

Specimen Volume: Full tube

Collection Instructions: Immediately place specimen on wet ice.


Seattle Children's Hospital Note:

Specimen must arrive within 72 hours of draw. Draw Sunday - Thursday only, DO NOT DRAW Fri, Sat, or on a holiday.

Specimen Type

Whole blood

Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole blood Refrigerated 7 days

Day(s) and Time(s) Performed

Monday through Friday; 8 a.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

Spectrofluorometric

Method Description

This evaluation is performed as a 2-step analysis. First, the total RBC porphyrin concentration is determined by extracting the porphyrins from washed, resuspended RBCs using a mixture of ethyl acetate and acetic acid. The porphyrins are then back extracted into dilute hydrochloric acid. Total porphyrins are quantified using this extract via spectrofluorometry.(Piomelli S: Free erythrocyte porphyrins in the detection of undue absorption of Pb and Fe deficiency. Clin Chem 1977;23:264-269)

 

If the total porphyrin concentration is elevated, the RBCs are re-extracted to separate and quantify the zinc-complexed and noncomplexed (free) protoporphyrin via high-performance liquid chromatography.(Smith RM, Doran D, Mazur M, Bush B: High-performance liquid chromatographic determination of protoporphyrin and zinc protoporphyrin in blood. J Chromatogr 1980 Mar 14;181[3-4]:319-327)

Reference Values

PORPHYRINS, TOTAL, RBC

<80 mcg/dL packed cells

 

FREE PROTOPORPHYRIN

<20 mcg/dL packed cells

 

ZINC-COMPLEXED PROTOPORPHYRIN

<60 mcg/dL packed cells

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

84311-Spectrophotometry, analyte not elsewhere specified

82542-Chromatography (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PEE Porphyrins Evaluation, WB In Process

 

Result ID Test Result Name Result LOINC Value
88886 Total Porphyrins, WB 2814-2
29356 Interpretation 59462-2

Testing Algorithm

This test is recommended for screening patients for possible erythropoietic protoporphyria and X-linked dominant protoporphyria. In addition, it can be used for evaluation of iron-deficiency anemia and chronic lead intoxication. Testing begins with total erythrocyte porphyrins. If the result is <80 mcg/dL, it is normal and testing is complete.

 

If the total erythrocyte porphyrin value is ≥80 mcg/dL, the protoporphyrin fractionation (PPFE) assay will automatically be performed at an additional charge. The PPFE test results include free protoporphyrin and zinc-complexed protoporphyrin.

 

The following algorithms are available in Special Instructions:

-Porphyria (Acute) Testing Algorithm

-Porphyria (Cutaneous) Testing Algorithm

Reject Due To

Hemolysis

Mild reject; Gross reject

Lipemia

NA

Icterus

NA

Other

NA

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
PPFE Protoporphyrins, Fractionation, WB Yes No

Forms

New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.